[Mkdump-devel] [patch] LAPIC/IO-APIC save/restore patch for testing

[Jan K. <la...@va...>]

Hi,

kexec patch uses APIC+IO-APIC reprogramming back to the original mode:
	http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.12-rc3/2.6.12-rc3-mm2/broken-out/x86-apic-virtwire-on-shutdown.patch
	http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.12-rc3/2.6.12-rc3-mm2/broken-out/x86_64-apic-virtwire-on-shutdown.patch

kexec locks up the child 'minik' kernel during:
	Calibrating delay loop...
if the parent 'mkexec' kernel is SMP running on VA-Linux-1220 machine.
FYI this machine has some broken BIOS IO-APIC settings.

mkexec uses modified patches above and it works fine even for VA-Linux-1220.
Still I do not understand the reasons. kexec solution looks right to me as if
IOAPIC is set to VirtualWire mode APIC LVT0 could get disabled. Unfortunately
not on VA-Linux-1220.

Legacy (PIC or VirtualWire) interrupts can be set in many ways by the BIOS and
I believe the most safe way is just to restore their state. Implemented in the
attached patch for LAPIC + IO-APIC by suspend/resume functions. Currently not
yet ready for non-i386, maybe on Friday.

Could you run it in some UP LAPIC-only / UP LAPIC+IO-APIC / SMP modes?

Or are there any affirmations that the current 'mkexec' double-way interrupts
are safe? APIC/IO-APIC doc pages 25-31:
	ftp://download.intel.com/design/pentium/datashts/24201606.pdf


Attached patches for 2.6.11 (in any order). To be applied on top of current
mkexec-module + linux-mkexecpatch; linux-mkexecpatch downloadable by:
	cvs -q -z3 -d:pserver:anonymous:@cvs.sourceforge.net:/cvsroot/mkdump rdiff -u -r bp_linux-2_6-mkexecpatch -r linux-2_6-mkexecpatch linux 
according to
	http://mkdump.sourceforge.net/cvs.html


Thanks,
Lace